Support Modern Remote Chrome

Starting in version 66, Chrome DevTools requires the host header to be “localhost” or an IP address. Work around this by setting the header to “lcoalhost” when fetching the version endpoint.

library/Pdfexport/HeadlessChrome.php

@@ -755,7 +755,7 @@ public function getVersion()
     protected function jsonVersion($host, $port)
     {
         $client = new \GuzzleHttp\Client();
-        $response = $client->request('GET', sprintf('http://%s:%s/json/version', $host, $port));
+        $response = $client->request('GET', sprintf('http://%s:%s/json/version', $host, $port), ['headers' => ['Host' => 'localhost']]);
 
         if ($response->getStatusCode() !== 200) {
             return false;